Low fuel pressure 95 volvo 940 turbo

Check the air valve, clean the throttle body, adjust the TPS, possibly replace the fuel pressure regulator after a fuel pressure test. Check the MAF: with the engine off, unplug it. Now start the car. Does it run 'better'? If so, the MAF is defective. You can also try cleaning it with MAF cleaner as well. Check the fuel system radio suppression relay (this is located either on the left or right side of the engine bay) is operating - cracked solder joints will also cause this misbehavior. You can easily verify this by swapping it with the AC fan relay next to it, otherwise 20 dollars will net you a new one.

Sometimes problems with the main pump (under the driver seat) check valve will cause this. A failed pre-pump will cause misfiring when cornering, especially right turns. A failed check valve results in low fuel pressure.

Rarely, the ignition crank angle sensor (top of bellhousing, rear of engine) is getting weak or the insulation has failed around the sensor, or possibly the connector is dirty.

Given this condition, also check the grounds on the fuel rail and along the front fenders as well.

the valve is only to test fuel pressure not for air. when you try to start the car the air will come out by itself just keep cranking untill the fuel makes it there

May have a faulty air/fuel ratio sensor or o2 sensor, throttle body may need adjusting or have a stretched spring or there may be grime restricting air flow so it's flooding it.

what were the specific inspection details like Co, 02, CO2 and NOx readings?

furthermore, have you done any maintenance like fuel filter, oil change and spark plugs?

I would replace the fuel pump relay, and the engine speed sensor. I would need more information to rule one or the other out, but at this mileage, neither part is terribly expensive, and both have been known to cause your same exact condition

Have you replaced your fuel pump relay?

I am a volvo tech and your problem is fuel pressure ralated and i had same problem in 1995 850 turbo and the fuel pump was the problem and a used one is around 35.00

If your air mass meter tests good, the I would tell you to check the HIGH PRESSURE PUMP underneath the Driver's side chassis pump holder-next to the fuel filter.

There are 2 pumps on your Volvo---the in-tank low pressure, and the chassis mounted high pressure. The car will run with the in-tank failed and the high pressure good. It will not run with the high pressure failed. Test the pump by applying voltage to the two terminals.

Another common failure, should the high pressure pump be good, is the HALL EFFECT SENSOR located in the distributor on the back of the engine. Once this sensor goes, it's no start. A rebuilt or used distributor may be the answer to your problem.

Hi, try fuel pump relay,......

Did you check your wiring, make a continuity test on the wiring,
clean all your ground wiring.
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